Capacitive sensor device and installations comprising a sensor device this type

ABSTRACT

A water supply for sanitary devices has a sensor, is activatable without contact, has a first capacitor with first and second conductive layers and a dielectric layer positioned there-between. A second capacitor having a first and second electrically conductive layers and a dielectric layer there-between. An AC voltage generator is electrically connected to the second layer of the first capacitor for coupling an AC voltage. The supply has a sensor amplifier for amplifying an output signal and the first layer is shared by the capacitors and has a shared absorption area. Upon approach or contact of an object or a liquid, an additional capacitor is formed whose effective capacitance experiences a detectable change that is tapped at the second layer.

The present patent application claims the priority of Swiss PatentApplication CH 2002 1353/02, which was filed on Aug. 2, 2002.

The present invention relates to capacitive sensors and sensor deviceswhich are particularly usable for detecting motions or objects. Itespecially relates to capacitive sensors and sensor devices which havean AC voltage signal applied to them and whose output signal is analyzedvia an amplifier stage.

BACKGROUND INFORMATION

There are essentially three different types of capacitive sensors. Thefirst variation is distinguished in that the capacitance C having itssensor area is the frequency-determining element in an oscillator. Afrequency shift, an amplitude change, or a damping increase is analyzedvia a corresponding method. The disadvantage of this method is a verynarrowly limited active region. A further disadvantage is theirsusceptibility to breakdown due to the influence of contamination and/ormoisture.

A second type of capacitive sensor is based on a repeating chargereversal of a defined DC voltage potential, in whose capacitance—timeconversion the charge reversal duration is analyzed. A disadvantage ofthis variation is a very narrowly limited response region. Furthermore,this principle has no static detection interval, but rather a dynamicdetection interval which is a function of the approach speed and theapproach angle of an object. An example of a sensor which is based onthe charge reversal principle is described in a publication ofEDISEN-electronic GmbH from 2001. This publication has the title“Schalten wie von Geisterhand—in der Zeitebene liegt der Zauber[Switching as if by magic—the magic is in the time plane]”. The analysismethod described in this publication is the object of a European PatentApplication which was published under the number EP 0 723 339 A1. Acomparable approach, which is based on the charge reversal principle, isdescribed in German Published Application DE 25 16 024. There is aGerman Published Application DE 198 15 324 A1, in which a sanitary valveis described that is designed so that through repeated charge reversaland determination of the charge reversal duration, the water supply maybe controlled.

A third type is capacitive barriers, whose geometric positioning of thetwo plates corresponds to an optical light barrier and which exploit thefact that a current flows between two capacitor plates when they arepowered with AC voltage. One possibility is to shield both plates fromone another through a conductive and grounded object. In this case, thecapacitive current becomes smaller or disappears entirely. In addition,the capacitance may be elevated if a non-grounded object is pushedbetween the two plates. In this case, the capacitive current becomeslarger. The disadvantage of this variation is that the object must belocated between the plates. A further disadvantage is the increasingsusceptibility to breakdown due to external influences with increasingplate spacing. The dependence of the AC voltage amplitude on the platespacing is also a disadvantage. A capacitive sensor for detecting thefill level of a liquid is described in German Published Application DE199 49 985.

A further arrangement for use in the sanitary field is described in U.S.Pat. No. 5,694,653. The arrangement described allows contact-lesscontrolling of the water supply and the temperature of the water in awashbasin. The valve is wired so that it acts as a transmitter whichemits electrostatic waves. If a user moves his hand toward the valve,the hand acts as a receiver of the electrostatic radiation. A large-areareceiver is positioned in the front region of the washbasin, which inturn absorbs the electrostatic radiation emitted from the body of theuser. A transmission circuit is thus closed and it may be detected thatthe hand has approached the valve. This type of arrangement is verysensitive and has a very complex construction.

OBJECT OF THE INVENTION

The present invention is therefore based on the object of providing asensor device, which both reduces or eliminates the disadvantagesdescribed in the related art and also has further advantages. Thepresent invention offers, among other things, the following advantages:larger response and active regions, strongly improved signal-to-noiseratio, detection of static and moving objects and their position in theactive region, independence from generator voltage amplitude in thefunction of the active region, and, since a non-grounded object does notinfluence the sensor unit, also a simple, unremarkable adaptation toexisting objects.

ACHIEVEMENT OF THE OBJECT

This object is achieved

-   -   for the sensor device by the features of claim 1; and    -   for installations by the features of claim 16. Advantageous        refinements of the present invention are defined by the        dependent claims.

In the following, the present invention will be described in greaterdetail with reference to the drawing:

FIG. 1A shows a first sensor device according to the present inventionin a schematic sectional illustration;

FIG. 1B shows an equivalent circuit diagram of the sensor device shownin FIG. 1A;

FIG. 2 shows a schematic illustration which displays the comparison of aconventional sensor and a sensor device according to the presentinvention under the effect of moisture;

FIG. 3A shows a schematic illustration which displays the active regionof a conventional sensor;

FIG. 3B shows a schematic illustration which displays the active regionof a sensor device according to the present invention;

FIG. 4A shows a second sensor device according to the present inventionin a schematic sectional illustration;

FIG. 4B shows an equivalent circuit diagram of the sensor device shownin FIG. 2A;

FIG. 5 shows a further sensor device according to the present invention,which has a similarity to the sensor device shown in FIG. 1A and 1B, ina top view;

FIG. 6 shows a further sensor device according to the present inventionin a sectional illustration;

FIG. 7 shows a further sensor device according to the present inventionin a sectional illustration,

FIG. 8 shows a further sensor device according to the present inventionin a top view;

FIG. 9 shows a further sensor device according to the present inventionin a top view;

FIG. 10 shows a further sensor device according to the present inventionin a top view;

FIG. 11 shows a further sensor device according to the present inventionin a sectional illustration;

FIG. 12 shows a further sensor device according to the present inventionin a sectional illustration;

FIG. 13 shows a simplified block diagram of a further sensor deviceaccording to the present invention;

FIG. 14 shows a further sensor device according to the present inventionin a top view;

FIG. 15 shows a water tap according to the present invention having asensor device in a side view;

FIG. 16 shows a urinal according to the present invention having asensor device in a detail view;

FIG. 17 shows an installation according to the present invention havinga sensor device for determining the fill level.

The schematic construction of the present invention is shown in FIG. 1A.A second electrically conductive area 41 is attached to a firstelectrically conductive area 32 using the insulator 43. Furthermore, athird electrically conductive area 31 is provided on the firstconductive area 32 using a second insulator 33. The electricallyconductive area 41 is connected via a connection 36 to an AC voltagegenerator 39. The electrically conductive area 31 is connected via aconnection 37 to a sensor amplifier 40.

The functional principle according to the present invention will beexplained in detail in connection with FIG. 1B: a generator signal s1(t)is coupled through the AC voltage generator 39 via C1, comprising afirst electrically conductive area 41, the dielectric 43, and a secondelectrically conductive area 32.3. The signal s2(t) is coupled out viaC2, comprising a first electrically conductive area 31, the dielectric33, and a second electrically conductive area 32.1, onto the sensoramplifier 40. The partial areas 32.1, 32.2, and 32.3 correspond in thearrangement described to the area 32 shown in FIG. 1A. A capacitance C3comprises the first area 32.2 and the dielectric in the range dx, which,in addition to ε₀ (for the air gap), may be composed from differentε_(r), as is shown, for example, in FIG. 1A using an adhesive layer 34and a carrier material 35, and the object 38. C3 changes its capacitanceas a function of dx, as a function of the construction of thedielectric, and also as a function of the object 38. In the extremecase, if there is no ε_(r) and there is direct contact of the object 38with the absorption area 32, C3 is replaced by a resistance R≧0.

The arrangement between the coupling point 36 for s1(t) and the point 37at which s2(t) is tapped forms the actual electrical network of thesensor device, C1 and C3 forming a voltage divider, whose central tapsupplies the signal s2(t) to the sensor amplifier 40 via C2. If theobject 38 approaches the area 32, dx is reduced and the effectivecapacitance of C3 is thus elevated. The signal s2(t) is thuscorrespondingly damped. If the object 38 moves away from the area 32, dxbecomes larger and the capacitance of C3 thus becomes smaller.Accordingly, s2(t) is damped less. Thus, the area 32 can be regarded asabsorption area. The dimension of the absorption area 32 is a functionof the application. The ratio of the dimensions of the electricallyconductive areas 31, 32, and 41 and their dielectrics 33 and 43 to oneanother are also a function of the application. The operating region ofthe sensor device may be optimized using voltage adaptation. Thisrequires a corresponding dimensioning of C1 in relation to C3. Theactive region of the sensor unit is essentially determined by itsabsorption area 32.

The response region of a conventional sensor device is compared with thesensor device according to the present invention in FIGS. 3A and 3B. Theconventional sensor device is shown below the diagram in FIG. 3A. Thesignal s2(t) is only attenuated when an object approaches the plates ofthe capacitor in a very narrowly limited region.

In the sensor device according to the present invention, which is shownbelow the diagram in FIG. 3B, the desired response region is set usingthe dimension of the absorption area and/or fixed thereby.

In order that the electrical field of C1 and C2 may not be influenced,or in the extreme case even short-circuited, both the electricallyconductive areas 31 and 41 and also their dielectrics 33 and 43 are tobe positioned behind the absorption area 32 and/or invisibly to theobject 38, as is shown in FIG. 1A. A direct comparison of a conventionalcapacitive sensor device and the sensor device according to the presentinvention are shown in this regard in FIG. 2. The behavior when thesensor unit is moistened is shown. The output voltage s2(t) of aconventional sensor unit is constant (curve 220) in the dry state. Assoon as moisture wets the sensor device, a short-circuit occurs and theoutput voltage jumps suddenly and achieves a maximum voltage smax.

In contrast, the sensor device according to the present invention isinsensitive to moisture. A short-circuit may not occur. The curve 221runs horizontally. If an object now approaches, the voltage s2(t) falls,since damping occurs due to C3. The conventional sensor device shows noreaction when the object approaches because of the short-circuit.

In the following, further embodiments of the present invention will bedescribed:

A further embodiment of the present invention is shown in FIG. 4A. Acomparison of FIG. 1A with FIG. 4A shows that C1 was replaced by aresistor R. The functional principle according to the present inventionwill be explained in detail with reference to FIG. 4B. The generatorsignal s1(t) is coupled in by an AC voltage generator 19 via theresistor R. The resistor R may, for example, be the output resistance ofthe generator 19. The signal s2(t) is coupled out via C2, comprising afirst electrically conductive area 12, the dielectric 13, and a secondelectrically conductive area 11, on a sensor amplifier 20. The partialareas 12.1 and 12.2 in the arrangement shown correspond to the area 12shown in FIG. 4A. The capacitance C3 comprises a first area 12 and adielectric in the range dx, which, in addition to ε₀ (for the air gap),may be composed from different ε_(r), as is shown, for example, in FIG.4A using an adhesive layer 14 and a carrier material 15, and the object18. C3 changes its capacitance as a function of dx, as a function of theconstruction of the dielectric, and also as a function of the object 18.In the extreme case, if there is no Er and there is direct contact ofthe object 18 with the absorption area 12, C3 is replaced by aresistance R≧0.

The arrangement between the coupling point 16 for s1(t) and the point 17at which s2(t) is tapped forms the actual electrical network of thesensor device, R and C3 forming a voltage divider, whose central tapsupplies the signal s2(t) to the sensor amplifier 20 via C2. If theobject 38 approaches the area 12, dx is reduced and the capacitance ofC3 is thus elevated. The signal s2(t) is correspondingly damped. If theobject 18 moves away from the area 12, dx becomes larger and thecapacitance of C3 thus becomes smaller. Accordingly, s2(t) is dampedless. The area 12 is thus referred to as the absorption area. Thedimension of the absorption area 12 is a function of the application.The ratio of R to C3 is also a function of the application. Theoperating region may be optimized using voltage adaptation. Thisrequires a corresponding dimensioning of R in relation to C3. The activeregion of the sensor unit is essentially determined by the size andshape of the absorption area 12.

In order that the electrical field of C2 may not be influenced, or inthe extreme case even short-circuited, the electrically conductive area11 and also its dielectric 13 are to be positioned behind the absorptionarea 12 and/or invisibly to the object 18, as shown in FIG. 4A. In thisregard, the resistor R is also to be attached behind the absorption area12. However, this construction has the disadvantage that in contrast tothe embodiment in FIG. 1A, there is no longer an electrical separationbetween the generator 19 and the absorption area 12.

A further embodiment 30 is that in the variation shown in FIG. 1A, thecapacitor C2 is replaced by a high-ohmic resistor. This embodiment isnot shown. The disadvantage of this construction variation is that thesensor amplifier is electrically connected to the absorption area.

A further embodiment of the present invention is shown in FIG. 5. Theembodiment 90 shown in FIG. 5 corresponds in some elements to those ofthe embodiment 30. For the sake of simplicity, these elements areidentified using identical reference numbers as in FIGS. 1A and 1B. Thesensor device 9 is distinguished in that a shielding area 112 isprovided. This shielding area 112 comprises a conductive material and ispreferably applied to either ground or mass. The shielding area 112 isdecoupled from the areas 31 and 41 of the capacitors C1 and C2 by twodielectric layers 104 and 113. Through the shielding area 112, theresponse region of the sensor device 90 may be fixed primarily on thesemi-space in front of the absorption area 32. Movements behind thesensor device 90 (in FIG. 5 above the shielding area 112) are notdetected. Interfering influences may thus be excluded or reduced.Simultaneously, the shielding area 112 acts as a shield againstelectromagnetic interference. The signal-to-noise ratio may thus beimproved. According to the present invention, an AC voltage signal s1(t)from an AC voltage generator 99 is coupled via a conductive connection96 into the area 41 of the capacitor C1. On the output side, a sensoramplifier 100 is connected via a conductive connection 97 to a plate 31of the capacitor C2. A signal s2(t) is coupled out of the capacitornetwork here.

A further embodiment 120 is shown in FIG. 6. The embodiment 120 shown inFIG. 6 corresponds in some elements to the embodiments 30 and/or 90. Forthe sake of simplicity, these elements are identified using theidentical reference numbers as in FIG. 1 and/or FIG. 5. The sensordevice 120 is distinguished in that it has a symmetrical responseregion. The response region extends into the semi-space above and thesemi-space below the sensor device 120 shown. The entire construction ismirror-symmetrical to a central plane (not shown) in this example. Inaddition to the capacitance C1, formed by the first absorption area 32,the dielectric 43, and the area 41, and the capacitance C2, formed bythe first absorption area 32, the dielectric 33, and the area 31, thesensor device 120 comprises two further capacitors C1′ and C2′, as wellas a second absorption area 122. The capacitance C1′ is formed by thesecond absorption area 122, the dielectric 123, and the area 41, and thecapacitance C2′ is formed by the second absorption area 122, thedielectric 124, and the area 31. According to the present invention, anAC voltage signal s1(t) is coupled into the capacitor network from an ACvoltage generator 129 via a conductive connection 126 using thecapacitors C1 and C1′, the capacitances of the capacitors C3 and C3′being a function of whether objects are located in the response region.On the output side, a sensor amplifier 130 is connected via a conductiveconnection 127 to the area 31 of the capacitors C2, C2′. A signal s2(t)is coupled out of the capacitor network here.

A further embodiment 140 is shown in FIG. 7. The embodiment 140 shown inFIG. 7 corresponds in some elements to those of the construction 30. Forthe sake of simplicity, these elements are identified using theidentical reference numbers as in FIG. 1A and FIG. 1B. The sensor device140 is distinguished in that the absorption area 142 is divided into 2through n electrically separated partial areas 142.1, 142.2, through142.n. The spatial response sensitivity in dx may thus be elevated as afunction of dL (spacing between the partial areas) and the number ofpartial areas 142.1, 142.2, through 142.n. However, the signal-to-noiseratio and the short-circuit behavior in the event of moisture as shownin FIG. 2 accordingly worsen. According to the present invention, an ACvoltage signal s1(t) from an AC voltage generator 139 is coupled via aconductive connection 136 into the area 141 of the capacitor C1. On theoutput side, a sensor amplifier 143 is connected via a conductiveconnection 147 to an area 144 of the capacitor C2. A signal s2(t) iscoupled out of the capacitor network here.

Various further embodiments may be assembled on the basis of theembodiments shown and described through modification and othercombinations of the individual elements. It is to be noted here that thefigures are schematic. The figures are not to scale.

In the description, reference was made several times to an object whosemotion and/or position within the response region is detectable. Theobjects may be body parts—for example, the hand of a user—or artificialor natural objects or liquids.

In addition, the sensor devices allow, among other things, therecognition of the following states and/or changes:

-   -   an object comes into the response region,    -   an object leaves the response region,    -   an object moves in the response region,    -   an object changes its size in the response region,    -   an object remains in the response region,    -   an object changes its composition in the response region.        Advantages of the Sensor Device:

The sensor devices according to the present invention essentiallycorrect the disadvantages of known arrangements, or reduce thedisadvantages detectably. The present invention has significantadvantages in relation to the already known devices.

The sensor device according to the present invention has a significantlylarger response and active region, since the active region is largelydetermined by the dimension and shape of the electrically conductiveabsorption area.

According to the present invention, a sensor is no longer simplyimplemented by a two-plate capacitor, but rather at least one fixed andone variable (and/or externally influenceable) capacitor are used. Thespatial response region may be intentionally tailored to externalconditions through the geometric shaping of the plates and through acorresponding positioning of the plates to one another. In this case,the response region may be predefined both in area and spatially.

The signal-to-noise ratio is improved multiple times by the directcoupling of the AC voltage s1(t) into the absorption area 32 via C1.

The sensor unit according to the present invention recognizes staticobjects and moving and/or moved objects and their position within theactive region, since a corresponding signal is generated using s2(t).

Using the sensor unit according to the present invention, a much largeractive region may be achieved in area using small generator voltages,e.g., between 2 volts and 5 volts (preferably 3 Vss).

The sensor unit according to the present invention is not influenced bynon-grounded objects, since due to the constructive arrangement of C1and C2, their field lines may not be influenced directly. Thus, forexample, moisture and/or water largely has no influence, since it onlycomes into contact with the electrically conductive area 32.

In the event of a rapid ambient humidity change (in the extreme casefrom air to water), in typical two-plate devices their dielectric maybecome conductive (short-circuit), or at least change very strongly. Ina device according to the present invention, the dielectric may only beinfluenced insignificantly in such a situation, since the moisture orthe water only influences the absorption area. Because of the relativelylow generator voltage, the devices according to the present inventionare suitable for battery operation.

A further advantage is also that due to the defining size of theabsorption area, the response region of the sensor device is largelyindependent of the dielectric of the carrier material. Therefore, adevice according to the present invention may be used on greatly varyingcarrier materials.

As is obvious from the following embodiments, the sensor unit accordingto the present invention may be modified. All embodiments described upto this point may be modified as follows.

A further embodiment 50 of the present invention is shown in FIG. 8 in atop view. The sensor device 50 shown has an L-shaped, conductiveabsorption area 52. Two capacitors C1 and C2 are seated on thisabsorption area 52. The capacitor C1 is formed by a part of theabsorption area 52 and by an area 51. A dielectric, which is not shownin FIG. 8, is located below the area 51. The capacitor C2 is formed byanother part of the absorption area 52 and by area 53. A dielectric,which is not shown in FIG. 8, is also located below the area 53. Aresponse region may be predefined by the size and shape of theabsorption area 52. The absorption area 52 may assume nearly any shape.It may be situated two-dimensionally or even three-dimensionally. Thesensor device 50 may again have a signal s1(t) applied to it by agenerator. An output signal s2(t) may be coupled out from the area 53 atthe capacitor C2. The function is comparable to the embodimentsdescribed previously. As soon as an object approaches the absorptionarea 52, for example, this approach may be detected. The position of C1and C2 in relation to the absorption area 52 may be determinedspecifically for the application. Care must only be taken that a minimumspacing is ensured between C1 and C2, so that the direct coupling to oneanother is negligible.

A further embodiment 70 of the present invention is shown in FIG. 9 in atop view. The sensor device 70 shown has a T-shaped, conductiveabsorption area 72. Two capacitors C1 and C2 are seated on thisabsorption area 72. The capacitor C1 is formed by a part of theabsorption area 72 and by a plate 71. A dielectric, which is not shownin FIG. 9, is located below the plate 71. The capacitor C2 is formed byanother part of the absorption area 72 and by an area 73. A dielectric,which is not shown in FIG. 9, is also located below the area 73. In theembodiment shown, the response region may be fixed through removal (forexample, by cutting off using scissors). An absorption area made of aconductive, flexible material is especially suitable. The absorptionarea 72 may, for example, be implemented as a film or metal sheet whichis cut to size on a carrier material (such as a wall of a space or a(ceramic) wall of a sanitary device) before the sensor device 70 isattached. In order to make attaching the absorption area 72 easier, theabsorption area 72 may be provided on one side with an adhesive film.With a suitable selection of the adhesive film, it may be usedsimultaneously as a dielectric of the capacitor C3. It is an advantageof the sensor device according to the present invention shown in FIG. 9that while being detached and/or cut to size, no changes must beperformed on the AC voltage generator and the input sensitivity. Theposition of C1 and C2 in relation to the absorption area 72 may bedetermined for the specific application. Care must only be taken that C1has a minimum spacing to C2, so that the direct coupling to one anotheris negligible.

A further embodiment of the present invention is shown in FIG. 10 in atop view. The sensor device 80 shown has three rectangular, conductiveabsorption areas 82.1, 82.2, 82.3. The absorption areas 82.1, 82.2, 82.3are electrically connected to one another via connections 84.1 and 84.2.Two capacitors C1 and C2 are seated on the absorption area 82.1. Thecapacitor C1 is formed by a part of the absorption area 82.1 and by anarea 81. A dielectric, which is not shown in FIG. 10, is located belowthe area 81. The capacitor C2 is formed by another part of theabsorption area 82.1 and by an area 83. A dielectric, which is not shownin FIG. 10, is also located below the area 83. In the embodiment shown,the response region may be distributed onto the partial areas 82.1,82.2, and 82.3. If these partial areas 82.1, 82.2, and 82.3 are selectedin different sizes, it may be differentiated using an appropriateanalysis device, with object distance dx remaining the same, whether anobject has approached the first, the second, or the third partial area.This is made possible because, due to their different sizes, each of thepartial areas also assumes a different effective capacitance when anobject is moved toward it. If one assumes, for example, that a handapproaches the first partial area 82.1, a first damping of the signals2(t) results. In contrast, if the hand approaches the second partialarea 82.2, the damping of the signal s2(t) is less. These differencesare recognizable by a suitable analysis device. However, thesedifferences are not uniquely recognizable under certain circumstances,since, for example, a small object in front of the first partial area82.1 may cause a similar damping as a somewhat larger object in front ofthe third partial area 82.3.

The embodiment shown in FIG. 10 may be modified, for example, byproviding the capacitor C2, which is used for coupling out, on an areaother than the partial area 82.1.

Possible Manufacturing Methods:

All embodiments may be manufactured using the following method.

The sensor devices according to the present invention may bemanufactured in greatly varying ways. Preferably, a dielectric material,such as epoxy, glass fibers, or plastic films, is used as an insulationlayer (e.g., layers 33 and 43 in FIG. 1A). The conductive absorptionlayer may be applied to this insulation layer. There are various methodsfor this purpose. Gluing a film on, vapor-depositing or sputtering on ametal coating, and application using electroplating are especiallysuitable. A circuit board having metal coating (for example, having acopper lamination) may also be processed through etching in such a waythat the absorption area receives the desired shape and size. Thecapacitors C1 and C2 may be applied to the back of the sensor device infurther steps. These capacitors may either be prefinished componentswhich are applied or they may be built up from individual layers.

Circuit boards 174 which are laminated on both sides with copper arealso suitable. A sensor device 170 as shown in FIG. 11 may bemanufactured there-from. The first copper lamination is processedthrough etching, for example, in such a way that an absorption area 172having the desired shape and size results. The second copper lamination,which is located on the other side of the circuit board 174, is texturedby etching in order to form an area 173 of the capacitor C2 and an area183 of the capacitor C1. The circuit board 174 is used as the dielectriclayer of the two capacitors C1 and C2. This device may, for example, beattached directly to a carrier layer 175. This carrier layer may be aceramic layer, for example. The mode of operation of the device 170 iscomparable, for example, to the device 30. The entire electronics system(generator, signal preparation and analysis, microprocessor) maypossibly also be integrated onto the same circuit board 174.

An example of the sensor device 190, which was implemented on a board194 laminated on one side, is shown in FIG. 12. The lamination isprocessed through etching, for example, in such a way that an absorptionarea 192 having the desired shape and size results. Two conventionalcapacitors C1 and C2 are used, which are connected to the absorptionarea 192 via an electrical connection. The input signal s1(t) is appliedto the input side of the capacitor C1 and the output signal s2(t) may becoupled out on the output side at the capacitor C2. The mode ofoperation of the device 190 is comparable, for example, to the device30. It is also to be noted that conventional capacitors may only be usedconditionally, since, depending on the application, they are notcommercially available in the required capacitance range. The capacitorspreferably have a capacitance which is <1 pF.

An absorption area made of a conductive, flexible material is especiallysuitable. The absorption area may, for example, be implemented as a filmor metal sheet which is cut to size on a carrier material (such as awall of a space or wall of a sanitary device) before the sensor deviceis attached. In order to make attaching the absorption area easier, theabsorption area may be provided with an adhesive film on one side. Ifthe adhesive film is selected suitably, it may be used simultaneously asthe dielectric of the capacitor C3.

EXEMPLARY FORMS OF ANALYSIS

One possible form of analysis may be inferred from FIG. 13. The blockdiagram of a sensor device 200 is shown. Originating from an AC voltagegenerator 209, the signal s1(t) is coupled into the network. On theoutput side, a chain having the following elements is provided: sensoramplifier 210, filter 201 (preferably a bandpass filter which istailored to the frequency of the signal s1(t)), AC/DC converter 202(rectifier), analog/digital converter 203, and microprocessor 204. Theelements of the embodiment may be characterized in greater detail asfollows: frequency of the signal s1(t) approximately 20 kHz; amplitudeof the signal s1(t) approximately 5 V; application factor of the sensoramplifier 210 approximately 300; resolution of the analog/digitalconverter 203 10 bit and sample rate 10 Hz; clock frequency of themicroprocessor 204 approximately 4 MHz and instruction time 1 μs. Theseare exemplary specifications.

A further possible form of analysis of a sensor device 150 according tothe present invention is shown in FIG. 14. This is a device 150 whichcomprises n individual absorption partial areas 152.1 through 152.n.Each of these absorption partial areas 152.1 through 152.n has the sameinput signal s1(t) applied to it in the embodiment shown. It is alsoconceivable that each absorption partial area 152.1 through 152.n hasits own input signal applied to it. The input signal s1(t) is coupledinto the capacitor network via the capacitor C1.1—comprising the area151.1, a dielectric, and the absorption partial area 152.1. Thecapacitors C1.2 through C1.n each comprise the areas 151.2, 152.2through 151.n, and a dielectric in each case. The partial signalss2.1(t), s2.2(t) through s2.n(t) are coupled out via the capacitorsC3.1, C3.2, through C3.n. The capacitor C3.1 is formed by the area153.1, a dielectric, and the absorption partial area 152.1. C3.2 isformed by the area 152.2, the dielectric, and the absorption partialarea 152.2. C3.n is formed by the area 153.n, a dielectric, and theabsorption partial area 152.n. The output signals s2.1(t), s2.2(t)through s2.n(t) are supplied to sensor amplifiers 160.1, 160.2, through160.n. After these output signals have been amplified, the amplifiedsignals are converted using A/D converters 161.1, 161.2, through 162.ninto digital signals. In the example shown, a microprocessor 162 isused.

Using suitable analysis routines, the microprocessor 162 may analyzewhether an object is located in front of one of the absorption partialareas 152.1 through 152.n. It may also determine in front of which ofthe absorption partial areas 152.1 through 152.n the object is located.Depending on the arrangement of the absorption partial areas 152.1through 152.n, not only a planar resolution, but rather also a spatialresolution may be achieved. In the example described, n is a naturalnumber greater than 1. Motions and motion directions may also berecognized.

An operational amplifier is preferably used as the sensor amplifier inconnection with the present invention. Ideally, the operationalamplifier allows the amplification factor to be adjusted. Therefore, thesensor amplifier may be set in such a way that downstream stages (suchas a coupling circuit for coupling the analog part of the sensor devicewith a downstream digital processing device) may be fed with a signalthat lies in a range which may be processed. The regulation and/or theautomatic adjustment may also be implemented in another way. The type ofwiring cited may be used together with any of the previously describedembodiments.

If a digital processing device (microprocessor or computer) is to beused in order to process the output signals of the capacitor sensordevice, an A/D converter is used which is preferably connecteddownstream from the sensor amplifier or the AC/DC converter. The A/Dconverter converts the analog output signal at the output of the sensoramplifier or a rectified signal into digitally coded signals. The A/Dconverter is to have a resolution of 8, 10, 12, or more bits. Theresolution has an influence on the precision of the A/D conversion.Depending on the embodiment, the A/D converter may have a parallel or aserial interface, via which a connection to the digital processingdevice (e.g., in the form of a microprocessor) is implemented, or it isalready integrated into the processing device.

Fields of Application:

The main field of application of the present invention is currently seenin installations which are applied in the sanitary field in the widestsense, including the laboratory field, measurement technology in thewidest sense, including level and position measurement, and in buildingtechnology in general. In connection with the present invention, theterm installation comprises at least one sensor according to the presentinvention and/or one sensor device according to the present invention, achain having processing elements, an energy source (power supply unit orbattery), and a downstream system to convert the detection into anaction (such as opening and closing an actuator (e.g., a valve oroverflow protector), displaying information, or turning devices, valves,and the like on or off).

In the sanitary field, there is a need for detecting motions andpositions without contact, for reasons of hygiene or operating comfort.Thus, for example, flushing a toilet bowl or a urinal bowl or turning onand off a water supply to a washbasin or sink, a shower stall, or abathtub may be regulated or controlled without contact. Using suitableembodiments of the present invention, the supply of both cold water andhot water may be regulated separately, so that a mixture is received ata desired temperature.

Water supply regulators and/or controls to sanitary valves in the publicarea are frequently subjected to vandalism by the user, and it is anadvantageous property of the present invention that water supplyregulators and/or controllers may be designed as vandal-safe using it.The present invention is also suitable for sanitary valves which arepredominately used by older people or the handicapped, since noapplication of force is necessary. In addition, with a suitableembodiment of the present invention, the region which a body part mustapproach may be implemented as relatively large, which allows actuationof sanitary valves by the handicapped.

In certain cases, it may be advantageous to provide an overflow safetyon sanitary valves. Using an overflow safety of this type, overfillingand/or overflowing of a sanitary valve may be prevented more reliablythan using an overflow opening, which may be clogged by contamination.

In the sanitary field, there is a need to be able to activate anddeactivate water supply valves without contact. Using the sensor device300 according to the present invention, the supply unit 301 (water tap)may be used directly as the absorption area, as is schematically shownin FIG. 15. The AC voltage signal is provided by generator 309 andcoupled into the tap 301 via a capacitor C1. An output signal is coupledout via a capacitor C2 and transferred to an amplifier 310. If a hand isbrought into proximity to the tap 301 (absorption area), the watersupply is turned on. If the hand is removed again, the water supply isinterrupted again. Thanks to the sensor device according to the presentinvention, having the elements C1, C2, the generator 309, and theamplifier 310, in contrast to the known capacitor sensor devices, thehands are already recognized from a relatively large distance. Thepresence and the removal of the hands may also be recognized perfectlyusing the sensor device according to the present invention, in contrastto the known capacitor sensor devices.

The embodiment shown in FIG. 15 may be improved further by also applyingthe AC voltage signal of the generator 309 to the medium (in the presentcase water) which flows out of the tap 301. The stream of water emittedthus has the generator signal applied to it and may be “blanked out” inthe analysis. The stream of water does not produce damping, but rathermay produce a slight signal amplification depending on the coupling ofthe generator signal. Better differentiation between water and, forexample, a hand is therefore possible. The AC voltage signal of thegenerator 309 may be applied to a metal part which is in contact withthe water emitted via a high-ohmic resistor and a capacitor, forexample.

The sensor device 400 according to the present invention may also beused to control a urinal, as is indicated in FIG. 16. In this case, anabsorption area 402 is attached behind a ceramic wall 401 of a urinal insuch a way that the presence of the user and/or the urine stream isrecognized as the object. The AC voltage signal is provided by agenerator 409 and coupled into the absorption area 402 via a capacitorC1. An output signal is coupled out via a capacitor C2 and transferredto an amplifier 410. If a hand is brought into proximity to the watertap 301 (absorption area), the water supply is turned on.

In building technology, using the present invention, even larger areas,such as walls and the like, may be laid out in such a way that objectsand, under some circumstances, also their position in front of theseareas are detectable. New possibilities thus result for intelligentsolutions in buildings in particular. For example, interactive areas maybe implemented using the present invention.

In an intelligent building equipped in this way, sensor devicesaccording to the present invention may be used to control elevators, forexample.

A further field of application of the present invention is in the doorautomation field. Through suitable positioning of the sensor device, theautomatic opening and closing of doors may be caused. Furthermore, thehazard region of the door may also be monitored, which prevents the doorfrom closing when a person is located in the hazard region.

A further field of application is in measurement technology. Using thepresent invention, a level measurement may be performed easily andwithout coming into contact with the medium 502, as is schematicallyshown in FIG. 17. By attaching a vertical absorption strip 503 to theoutside of a non-conductive container 501, the corresponding level maythus be determined easily, since the absorption increases as a functionof the absorption area 503 covered by the medium 502. In the embodiment500, the AC voltage signal is provided by a generator 509 and coupledinto the absorption area 503 via a capacitor C1. An output signal iscoupled out via a capacitor C2 and transferred to an amplifier 510.

A system for leak recognition may also be implemented. For this purpose,the device according to the present invention is positioned in theregion of a container to be monitored. Liquid or another medium escapingdamps the field and may thus be detected. If a light generator signal isapplied to the medium, as described in connection with FIG. 15, thesystem may differentiate liquid which has escaped from the containerfrom other liquids.

A field of application which may also be included in measurementtechnology is position measurement. Since the present invention may alsodetermine distances up to several tens of centimeters, a positionmeasurement of an object or in relation to an object may be implemented.

A broad field for situating the sensor device according to the presentinvention is the kitchen field, for which combined sensor devices, suchas those shown in FIG. 14, are particularly suitable. Various kitchendevices may thus be turned on and/or off or switch positions may even bechanged. If the novel sensor device is used in the kitchen field, itscontactless actuation is especially advantageous; working in the kitchenfrequently results in dirty hands and sometimes requires suddenactuation of a device; if such an actuation must be performed viacontact, the device is subsequently dirtied, which may be avoidedthrough controls having the sensor device according to the presentinvention.

Call systems may also be controlled with the aid of sensor devicesaccording to the present invention. With arrangements as shown in FIG.10, it is additionally possible to selectively operate a call system.

A field of application which may also be included in building technologyis the security field. The sensor devices according to the presentinvention may be used in a similar way as heat sensors, but arecompletely unremarkable, so that an unauthorized person is preventedfrom bypassing them or even shutting them down. For example, dangerousregions, such as machines or the like, may be secured by a sensordevice. The sensor device may cause the machine to be turned off.

It is also possible to implement person monitoring using a foot mat,which has a capacitor plate or film as the foot mat. If a person stepsonto this mat, the generator signal is damped.

As it is desirable for reasons of hygiene to actuate the control of thewater supply to sanitary valves without contact, it may be advantageousin the medical field, particularly in operating rooms, to controlgreatly varying devices of medical technology without contact.

In the widest sense, irrigation systems, possibly with fertilizersupplies, of nurseries or agrotechnical experimental fields, forexample, even in greenhouses, may also be included in the sanitaryfield. Advantageous arrangements may be implemented for this purpose,particularly having a sensor device as shown in FIG. 10. The regionswhich trigger a reaction of the sensor device when approached arepositioned inside a map representation of the ground to be irrigated,the partial areas 82.1, 82.2, and 82.3 of the sensor device lying inpartial regions of the map illustration. The control of an irrigationsystem is therefore very visible and simple.

1-20. (canceled)
 21. A water supply for sanitary devices, which isequipped with a sensor device (30) and is activatable without contact,comprising: (a) a first capacitor (C1) having a first and secondelectrically conductive layer (32 and 41) and having a dielectric layer(43) positioned there-between; (b) a second capacitor (C2) having afirst and second electrically conductive layer (32 and 31) and having adielectric layer (33) positioned there-between; (c) an AC voltagegenerator (G), which is electrically connected to the second layer (41)of the first capacitor (C1), for coupling in an AC voltage signal(s1(t)); and (d) a sensor amplifier (A) for amplifying an output signal(s2(t)); and wherein the first layer (32) is shared by the twocapacitors (C1 and C2) and comprises a shared electrically conductiveabsorption area (32.2) or is electrically or capacitively connected tosaid shared absorption area (32.2), which, upon approach or contact ofan object (38) or a liquid, forms an additional capacitor (C3) whoseeffective capacitance experiences a detectable change that is tapped atthe second layer (31) of the second capacitor (C2) in the form of acorrespondingly changed output signal (s2(t)).
 22. The water supplyaccording to claim 21, further comprising a water supply tap (301) ormetallic parts of said water supply tap, forming as the absorption area(32.2) which is electrically or capacitively connected to the firstlayer (32).
 23. The water supply according to claim 21, wherein the ACvoltage signal (s1(t)) of the generator (G) is also applied to a mediumflowing out of a tap (301).
 24. The water supply according to claim 21,in combination with a sanitary device selected from the group consistingof: a toilet; a urinal; a washbasin; a sink; a shower; and a bathtub.25. The water supply according to claim 21, wherein the first layer (32)comprises a shared electrically conductive absorption area (32.2) and ispositioned as a film behind a wall of a sanitary device.
 26. The watersupply according to claim 25, wherein the wall of the sanitary device isa ceramic wall (401) of a urinal.
 27. An installation (500), equippedwith a sensor device (30), for level measurement in or on liquidcontainers (501), comprising:(a) a first capacitor (C1) having a firstand second electrically conductive layer (32 and 41) and having adielectric layer (43) positioned between them; (b) a second capacitor(C2) having a first and second electrically conductive layer (32 and 31)and having a dielectric layer (33) positioned there-between; (c) an ACvoltage generator (G), which is electrically connected to the secondlayer (41) of the first capacitor (C1), for coupling in an AC voltagesignal (s1(t)); and (d) a sensor amplifier (A) for amplifying an outputsignal (s2(t)); and wherein the first layer (32) is shared by the twocapacitors (C1 and C2) and comprises a shared absorption area (503), anadditional capacitor (C3) being formed upon filling of the container(501) with a medium (502), whose effective capacitance experiences adetectable change corresponding to the fill level, which is tapped atthe second layer (31) of the second capacitor (C2).
 28. An installation(500) for level measurement in liquid containers (501) according toclaim 27, wherein a vertical absorption strip (503) is attached to anoutside of a non-conductive water container (501) of a sanitary device,the sanitary device comprising at least one of a toilet and a urinal.29. An installation (500) for level measurement in liquid containers(501) according to claim 27 in combination with and for leak detectionin a region of a container to be monitored.
 30. An installationaccording to claim 29, including means for generating a low voltagesignal and wherein the medium stored in the container has the lowvoltage generator signal applied thereto.
 31. A facility (50) forrecognizing persons, having a sensor device (30), comprising: (a) afirst capacitor (C1) having a first and second electrically conductivelayer (32 and 41) and having a dielectric layer (43) positionedthere-between; (b) a second capacitor (C2) having a first and secondelectrically conductive layer (32 and 31) and having a dielectric layer(33) positioned there-between; (c) an AC voltage generator (G), which iselectrically connected to the second layer (41) of the first capacitor(C1), for coupling in an AC voltage signal (s1(t)); and (d) a sensoramplifier (A) for amplifying an output signal (s2(t)); and wherein thefirst layer (32) is shared by the two capacitors (C1 and C2) andcomprises a shared absorption area (52), an additional capacitor (C3)being formed upon tho approach or contact of a person to the absorptionarea (52), whose effective capacitance experiences a detectable changethat is tapped at the second layer (31) of the second capacitor (C2).32. The facility (50) for recognizing people according to claim 31,wherein the first layer (32) having the shared absorption area (52) isincorporated into a floor, wall, or ceiling covering or positionedthereon.
 33. The facility (50) for recognizing people according to claim31, wherein the recognition of a person opens or closes a door.
 34. Thefacility (50) for recognizing people according to claim 32, wherein theshape and size of the first layer (32) having the shared absorption area(52) are tailored to the conditions.